Method of tipping projectiles



Aprill w, 1945.

R. K. HOPKINS METHOD OF TIPPING FROJECTILES Filed March 2, 1943 INVENTOR K066 1 517 gofi'a'rw ATTORNEY atented Apr. 10, 1945 METHOD OF TIPPING PROJECTILES Robert K. Hopkins, New York, N. The M. W. Kellogg Company,

Y., assignor to New York, N. Y.,

a corporation of Delaware Application March 2, 1943, Serial No. 477,737

I Cl. 117-52) Claims.

The present invention relates to a method of tipping metal bodies, and more particularly to a method of tipping the cores of small projectiles or bullets.

In certain forms of small projectiles or bullets such as those of th copper jacketed type, it is desirable to provide a core of extremely tough metal which does not fracture upon impact, and a tip made of a metal which is extremely hard andwhich therefore is not easily workable.

One object of the present invention is to provide a new and improved method of tipping metal bodies.

Another object is to provide a new and improved electric fusion method of tipping a small projectile core with metal having an analysis different from that of the core to produce an integral projectile having core and tip segments of required physical characteristics.

In carrying out the method of .the present invention, the projectile core is moved into spaced proximity to a bath of molten metal of an analysis suitable for producing a tip of desired analysis, and electric current discharged through said core and said metal bath and across the intervening gap to fuse one end of the core. The fused core end is then dipped into the metal bath, the electric current shut off and the core withdrawn from the metal bath. As this core is so withdrawn, some of the metal from the bath adheres closely to and is integrally consolidated with the fused end of said core, and when solidified forms a tapering tip on said core.

As another feature of the present invention, the bath of molten metal is maintained under a protective blanket of flux, and the fusion current discharged from the core while said core is submerged in said flux.

Various other objects, features and advantages of the invention will be apparent from the following particular description, and from an inspection of the accompanying drawing, in which Fig. l is a horizontal section of an apparatus which may be employed to carry out the method of the present invention; and

Fig. 2 is a vertical section of the apparatus taken on line 2-2 of Fig. 1."

The method of the present invention is carried out in a furnace l0 containing a bath of molten metal ll of the analysis required to produce the projectile tip of desired analysis. This furnace I0 may be of fire clay, graphite or other suitable refractory material as shown, or may be of metal cooled by a suitable cooling medium such as water.

ill

The molten metal II is of hardenable composition. and for that purpose may contain carbides of such metal as titanium, tantalum and tungsten. This metal Ii is kept in molten condition in the furnace III by any suitable means. For instance, one or more electrodes I2 spaced from the surface of the metal II by a current discharge gap and submerged in a protective blanket of flux I3, may be employed to generate enough heat in the furnace ill to maintain said metal in fluid state. These electrodes I2 may be of the consumable or non-consumable type, and the metal I I grounded or otherwise connected in the circuit of said electrodes. As the metal Ii is expended in producing the projectile tips, replenishment is effected by the addition of the necessary ingredients in the metal bath. If the electrodes I2 are of the consumable type shown, these may furnish at-least part of the ingredients of the metal bath I I, and may be of tubular construction as shown, in which case the other necessary ingredients may be supplied in fluent form into the furnace in through the respective hollows of said electrodes.

The molten flux or slag is which floats on the surface of the metal bath II, refines the fused metal, protects the metal against atmospheric contamination and insulates it against rapid heat losses. This flux I3 may be of any suitable composition which does not produce an objectionable amount of gas under the influence of an electric discharge. Flux comprising silicates or components of silicates, such as manganese silicate, calcium silicate, aluminum silicate, glass and the like have been found suitable for this purpose.

A projectile core I5 to be tipped is removably clamped in an electrode chuck or holder I6 connected in the electric curcuit of the metal bath II, and is of extremely tough metal which does not fracture upon impact. From position A, the core I5 is submerged in the flux l3 into position B with the lower end of said core spaced from the upper surface of the metal bath I I by a current discharge gap. During the movement of the core l5 from position A to position B, the core fusing current is on, and when said core reaches position B, current is discharged from the lower end of said core and across the gap. This current discharge generates enough heat to fuse the lower end of the core I5. After proper fusion of the core end in position B, the core end is immersed in the metal bath II by being moved into position C. The fused core end is protected from atmospheric and other contamination by the flux I3, and is therefore in proper condition for eflective consolidation with the tip metal of a the bath i I when immersed therein in position C.

sired tapering form by any suitable means, as for example by a grinding operation.

During the tipping operation described, some of the fused metal of the core II will be deposited inand admixedwith the metal bath II. The analysis of this metal bath ll, however, may be Asthecoreliis held constant by means of the electrodes l2 and the addition of other ingredients if necessary.

The tipping operation may be recurrently car ried out automatically by supporting four cores I! in the difierent positions shown, and moving these cores simultaneously into their next successive positions. These cores I! may be operated intermittently into diflerent successive positions, and the operations in positions B and C carried out during pauses in the movement of said cores.

If desired, the cores I! may be moved continuously without cessation through the difierent positions. For example, during phase B, the core I! in that phase may be moved continuously over the surface of the metal bath il while current is being discharged across the gap with the gap maintained of a substantially constant width. When the desired fusion of the core end has been produced, the fused core I! can be dipped into the metal bath in phase'C without interrupting movement of the core towards one side of the furnace l0.

The method of the present invention can be applied to the tipping of small arm cores, as for example those employed in cartridges of the copper jacketed type, or may .be employed to tip the cores of projectiles of larger sizes. A far as certain aspects of the invention are concerned, my method may be employed to apply a head, appendix or tip on a. metal body of any other form or shape.

As many changes can be made in the above method, and many apparently widely different embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. The method of tipping a metal body which comprises fusing one endof said body by subjecting said end to electric current discharge while said end is submerged beneath the surface oi a depth of molten flux. immersing the fused end of 881d body in a. blfl'i 0f molten metal hi7!!! am-analysis diiferent from that'ot said metal body. and withdrawing said metal body from said bath with metal from said bath adhering to and integrally consolidated with the fused end of said metal body.

2. The method of tipping a metal body which comprises submerging one end of said metal body in a blanket of flux floating on a bath of molten metal, discharging electric current through said metal body and said metal bath and across the intervening gap submerged in said flux to fuse the flux submerged end of said body, immersing the fused end of saidbody in said bath, shutting oi! the fusion current, and withdrawing said body from said bath with metal of said bath adhering to and integrally consolidated with the fused end of said body.

3. The method of tipping a metal body which comprises producing a bath of molten metal under the current discharge action of an electrode submerged in a protective blanket of iiux, submerging one end of said metal body in said flux. discharging electric current through said metal body and said metal bath and across the intervening gap submerged in said flux to fuse the flux submerged end of said body, immersing the fused end of said body in said bath, shutting of! the fusion current, and withdrawing said body from said bath with metal of said bath adhering to and integrally consolidated with the fused end of said body.

4. The method of tipping a projectile core which comprises discharging fusion current across a gap intervening between the core and a bath of molten metal to fuse one end ,of' f said core while maintaining said gap and. said bath of molten metal beneath a depth of molten flux, immersing the fused end of said core in said'bath, shutting off the fusion current, and withdrawin said core from said bath with metal of thebath clinging to and consolidated with the fused end -of said core to form a tip for said core.

ROBERT K. HOPKINS. 

